This invention relates generally to a machine for severing standing crops from the ground to initiate a harvesting process and, more particularly, to a rotary disc cutterbar having a preselected number of transversely oriented, rotatable discs interconnected by shafts and a method to improve the durability of splines on the interconnecting shafts.
One type of disc cutterbar used in agriculture includes a plurality of elongated modular housings each containing a bevel gear set for delivering power to respective modular cutterheads spaced along the length of the cutterbar. Power is transferred from the vehicle power take-off to adjacent modules by a plurality of connecting shafts. The cutterheads each comprise a cutting disc including diametrically opposed cutting blades (though configurations with three or more blades are known) and having a hub coupled to an upper end of a drive shaft, the lower end of the drive shaft carrying a bevel gear. The connecting shafts utilize splined shaft connections to pinon gears which in turn engage the bevel gears and allow power to be transferred along the width of the cutterbar. For background information on the structure and operation of some typical disc cutterbars, reference is made to U.S. Pat. No. 5,996,323, issued to Campbell, the descriptive portions thereof being incorporated herein in full by reference.
Current cutterbar production and assembly methods allow the connecting shafts to freely float between adjacent modules which have led to durability concerns. Absent a biasing element to center the shaft laterally between adjacent modules, the connecting shafts may laterally shift to one end or oscillate in a position. The spline connection is currently lubricated with grease during assembly which over time may lead to operational conditions in which inadequate lubrication is present in the connection. Oscillating movement can lead to fretting of the splines. Left unchecked, the tolerances in the splined connection may degrade to a point at which the connecting shaft may no longer rotate about its axial centerline. Shaft rotation about a slightly eccentric rotational path results in increased vibration which speed degradation of other components within the driveline. Further, a connecting shaft that has shifted laterally toward one module results in differing engagement areas between the two splined end connections which results in uneven wear between the connecting shaft splined ends.
It would be advantageous to have an improved modular cutterhead connecting shaft configuration which would improve the durability of the connecting shaft splined end connections with adjacent cutter modules. Further advantages would be realized by an connecting shaft splined end connection that utilized lubricant retained in the module gearbox housing to provide periodic lubrication of the splines. Still further advantages would be realized through the inclusion of apparatus to maintain the connecting shaft ideally positioned between adjacent cutterhead modules.